I would think the 7970 will perform better overall once you start overclocking it.
The 670 however might be quieter because of the nature of that GPU.
If it's the same price and you don't think you'll ever go SLI/CF, I'd probably go for the 7970 because of the additional VRAM.

I'm no expert but I believe the VRAM is not a proper judge? Maybe for multi monitor it is but I don't know. I'm just saying this because for example a 6970 has 2gb of vram and a gtx 570 has 1.28gb where as they give roughly the same performance and are in direct competition with eachother.

On a side note why is it that Nvidia's less VRAM performs as well as AMD's more VRAM?

You would only need 3GB of VRAM if you're running 3 or 6 monitors. For a single monitor, even a 27" or a 30", 2GB will be more than enough video memory. Hell, even 1GB is most likely enough for any single monitor (30" might be pushing it though).

Amount of video memory is NOT indicative of card performance. I just bought a 5450 that says 1GB on the box, but in actuality the card has 1/20 the performance of a 6850. So in otherwords, even though it's 'a 1GB video card' it's actually incapable of running even the most basic game. Another example: the GTX680 2GB blows the 7970 3GB out of the water in almost every metric. The only place it might fall short is when running two or three of them together in order to drive three or six monitors.

You want to look for is the number of graphics cores, ROPs, and texture units, as well as the overall efficiency and power consumption of the card. Look at the reviews to determine which card suits your needs best.

I do plan on running 3 monitors, but only the Catleap 1440p for gaming. Is this a game changer?

Quote:

Originally Posted by great_big_abyss

You would only need 3GB of VRAM if you're running 3 or 6 monitors. For a single monitor, even a 27" or a 30", 2GB will be more than enough video memory. Hell, even 1GB is most likely enough for any single monitor (30" might be pushing it though).

Amount of video memory is NOT indicative of card performance. I just bought a 5450 that says 1GB on the box, but in actuality the card has 1/20 the performance of a 6850. So in otherwords, even though it's 'a 1GB video card' it's actually incapable of running even the most basic game. Another example: the GTX680 2GB blows the 7970 3GB out of the water in almost every metric. The only place it might fall short is when running two or three of them together in order to drive three or six monitors.

You want to look for is the number of graphics cores, ROPs, and texture units, as well as the overall efficiency and power consumption of the card. Look at the reviews to determine which card suits your needs best.

It's only a game changer if you're gaming on three large monitors (27-30"+). If you're running desktop on 2 monitors, and gaming on your center monitor, you'll be fine. You won't even come close to utilizing all of your Vram.